Embryos of Homarus americanus are Protected by Epibiotic Bacteria

Embryos of the American lobster, Homarus americanus, are remarkably resistant to infection by the fungus Lagenidium callinectes, a pathogen of many crustaceans. The surfaces of healthy lobster embryos are covered almost exclusively by a single, Gram-negative bacterium, which grows in a dense mosaic pattern. In culture, this bacterium produces a compound that completely inhibits the growth of the pathogenic fungus in vitro at 10 mcg/ml. Large-scale fermentation, extraction, and subsequent chromatographic purification led to the identification of the antifungal substance as 4-hydroxyphenethyl alcohol (tyrosol), an antibiotic substance known to be produced by terrestrial fungi.